1. Technical Field
The present disclosure relates to a periodic magnetic field generator having main permanent magnets magnetized in a direction of generated magnetic field, and auxiliary permanent magnets magnetized in a direction different from the main permanent magnets, wherein the main permanent magnets and the auxiliary permanent magnets are disposed alternately. The present disclosure also relates to an actuator equipped with the periodic magnetic field generator.
2. Description of the Related Art
Periodic magnetic field generators are used as devices that generate magnetic fields for driving various actuators such as image-capturing devices equipped with camera-shake correction mechanism, automatic focus (AF) mechanism, zoom mechanism and the like, robots, and motors. There is a growing demand in recent years for the periodic magnetic field generators to generate magnetic fields of increased density of magnetic flux in order to obtain higher driving force.
Patent Literature 1, for instance, discloses a periodic magnetic field generator including a back yoke, main-pole permanent magnets having upward and downward directions of magnetization, auxiliary-pole permanent magnets having rightward and leftward directions of magnetization, and soft magnetic materials disposed on magnetic-field generation sides of the main-pole permanent magnets. According to this periodic magnetic field generator, the influence of magnetic saturation in the magnetic circuit is alleviated by the soft magnetic materials because the generated magnetic field is directed upward (i.e., Z-axis), thereby achieving an increase in the generated magnetic field as compared to a structure having only a Hull Bach magnet array.